topic Re: DL380G6 Memory Config Rules in ProLiant Servers (ML,DL,SL)

DL380G6 Memory Config Rules

Toyo_1 — Fri, 31 Jul 2009 05:24:22 GMT

Been through the Mem Config tool and are trying to understand why a 491332-371 base server (1 CPU, 3 x 2Gb modules) when upgraded to 2 CPUs with 16Gb total (i.e. original 3 x 2Gb modules plus 2 x 4Gb (500658-B21) plus 1 x 2Gb (500656-B21)) ends up with 10Gb on one CPU and 6Gb on the other.
i.e. config tool has CPU 2 Ch1 2Gb + 2Gb, Ch2 4Gb + 2Gb and CPU 1 Ch1 2Gb, Ch2 4Gb.

Why have 2 modules on Ch1 and Ch 2 for CPU 2 and not 1 module per channel for both CPUs? i.e. CPU 1 & CPU 2 - Ch1 2Gb, Ch2 2Gb, Ch3 4Gb

Re: DL380G6 Memory Config Rules

asqwq — Sat, 01 Aug 2009 09:19:50 GMT

hi
you can read user guide for dl380 g6 on this address:
http://www13.itrc.hp.com/service/cki/docDisplay.do?docLocale=en&docId=emr_na-c01705681-2

Re: DL380G6 Memory Config Rules

Toyo_1 — Mon, 03 Aug 2009 04:14:26 GMT

If I read the user guide correctly then the above config is recommended because it allows the memory to operate in either Mirrored or Lockstep mode (both of which don't allow Ch3 to be populated).
If however I don't necessarily want to utilise either of those modes then am I correct is assuming that I could actually populate then memory as CPU 1 & CPU 2 - Ch1 2Gb, Ch2 2Gb, Ch3 4Gb - albeit leaving the server with reduced memory redundancy.

Re: DL380G6 Memory Config Rules

Dhanesh Amirthalingam — Mon, 03 Aug 2009 07:18:54 GMT

Memory configuration and population rules and logic..
â ¢ There are many rules governing how DDR3 memory should be installed in a server.
â ¢ Factors that determine how DIMMs may be installed include:
â ¢ DIMM type, DIMM rank, clock speed, position to the processor (closest/furthest), number of memory channels, and desired redundancy features.
DDR3 Memory comes in two types; RDIMM and UDIMM.

RDIMM or Registered - Maximum server capacity up to 144GB
â ¢ Larger capacities and include address parity protection & advanced memory protection.
â ¢ Less electrical load on the memory controller; allows systems to remain stable with more memory modules.
â ¢ Used for applications requiring scalability and stability.
UDIMM or Unbuffered - Maximum server capacity up to 24GB.
â ¢ Lower power consumption, limited in capacity but lower in price.
â ¢ Uses SDRAM chips directly connected to memory controller without a buffer.

http://h18004.www1.hp.com/products/servers/options/tool/hp_memtool.html

I think it ill help you out lotâ ¦â ¦.

Re: DL380G6 Memory Config Rules

Pieter 't Hart — Mon, 03 Aug 2009 08:03:26 GMT

I think another criterium counts : look at page 45.
when all 3 slots of a channel are used, memory speed is reduced.
Therefore 2 slots each of 3 channels are populated on processor-1. and 2 slots of 2 channels for processor-2.

Re: DL380G6 Memory Config Rules

Toyo_1 — Mon, 03 Aug 2009 22:14:55 GMT

I understand that. What I'm proposing is to use one slot on each of the three channels on each CPU.
i.e. 6 DIMMs - 1 in each of slot 1 on Ch1, Ch2 & Ch3 on each CPU.

Re: DL380G6 Memory Config Rules

Pieter 't Hart — Wed, 05 Aug 2009 06:24:23 GMT

Sorry if i misunderstood.

The user guide confirms your choice would be allowed:
For Advanced ECC mode configurations with multiple processors, populate the DIMM slots for each processor in the following order:
â ¢ RDIMM: Sequentially in alphabetical order (A through I).
=> A-B-C is one module per channel.

There may be a criterium not explained in the manual why the tool prefers to populate two slots per channel or to leave channel-3 preferably unused (for cpu1 and not for cpu2).

There are other posts about the mem config tool suggesting it has (a) bug(s) => better contact HP about this.

Re: DL380G6 Memory Config Rules

Toyo_1 — Wed, 05 Aug 2009 22:37:13 GMT

No worries Pieter. Thanks for making the effort to respond. Much apreciated.

The config tool suggests -
CPU 1 Ch1 2Gb, Ch2 4Gb
CPU 2 Ch1 2Gb + 2Gb, Ch2 4Gb + 2Gb

The fact that it leaves Ch3 empty on both CPUs suggests to me that the tool prefers mirroring or lockstep which kinda makes sense. Dosn't explain why it didn't suggest the following config (i.e. split the memory equally across CPUs)-
CPU 1 Ch1 2Gb, Ch2 4Gb + 2Gb
CPU 2 Ch1 2Gb, Ch2 4Gb + 2Gb

Will discuss further with suppliers engineers.

Re: DL380G6 Memory Config Rules

KJ C — Mon, 21 Jun 2010 17:22:36 GMT

could I configure Box 1
A, B, C (8GB)
D (2GB)
E (2GB)
&
F (4GB)

that would be a total of 64GB

Box 2
A, B, C (2GB)
D (2GB)
E (2GB)
&
F (4GB)

that would be a total of 20GB

Box 3
A, B, C (2GB)
D (4GB)
that would be a total of 20GB

thanks